Pipe collars of the general type herein concerned are known in the art. It is known, for example, to provide a pipe collar having first and second arcuate shell members with clamping means for drawing the shell members together around a pipe. It is further known to provide first and second elastomeric arcuate sealing means respectively disposed interiorly of each shell member, and wedge members disposed between the shell members and adapted to slide on interior surfaces of the shell members as the shell members are drawn together by the clamping means. Each of the arcuate sealing means are known to comprise a pair of circumferential sealing strips spaced apart, and interconnected, by axial sealing strips which slidingly engage the interior surfaces of the shell members, and by axial end sealing strips, two of which contact each other to form a seal between two opposed ends of the sealing means. It is known that both sets of axial sealing strips are disposed in grooves in the wedge members. A pipe collar of this construction is shown and described in British Patent No. 2,189,000, published Nov. 22, 1989, in the name of Robert W. Jardine.
In the Jardine pipe collar, each of the end sealing strips is disposed in an axial, or longitudinal, groove in the end of a wedge member. Each end sealing strip is rectangular in width-wise cross section and upstands from the wedge member end surface in which its respective groove is located. In an effort to encourage pairs of opposed end sealing strips to properly engage one another, each wedge member is provided at its end with inclined width-wise extending ramp surfaces adapted to engage with oppositely inclined ramp surfaces of the opposite wedge. While the ramp surface arrangement may be beneficial with respect to correction of width-wise misalignment of the end sealing strips, it is not instrumental in leading to proper length-wise alignment of the end sealing strips, and thereby the two sealing means. Further, because of the rectangular shape of the end sealing strips, the goal of the ramp surfaces is sometimes thwarted by a side-by-side mating of two end sealing strips.
In the Jardine pipe collar, each of the sliding sealing strips is rectangular in cross section and is wholly contained within its groove in its wedge member. Because the sliding sealing strip is substantially flush with the wedge member surface, its sealing effectiveness is minimal.
Additionally, the circumferential sealing strips of the Jardine collar are substantially flat on the side of the strip that contacts the pipe. Thus, substantial force must be applied to conform the thick, rigid ends of the strip to the pipe. This creates undesirable stresses within the collar, and makes assembly difficult.
Moreover, when the Jardine pipe collar is used with pipe large enough in diameter to require stretching of the circumferential sealing strips, it often happens that the ends of the sliding sealing strips, at their junctures with the circumferential sealing strips, are pulled from their respective grooves in the wedge members, opening leakage avenues between the pipe and the collar, greatly lessening the effectiveness of the sealing means.
Accordingly, it is deemed beneficial to provide a pipe collar of general construction similar to Jardine's, but having improved sealing capabilities, and in particular, sealing capabilities overcoming the inadequacies of the Jardine collar.